The field of the invention pertains to pressure sensors for measuring in real time pressure inside internal combustion chambers in engines and, in particular, fiber optic pressure sensors in spark plugs and glow plugs.
By providing an aperture in a glow plug for a fiber optic pressure sensor, a separate aperture into the combustion chamber is not necessary. However, the glow plug environment can be extreme with instantaneous temperatures in thousands of degrees Fahrenheit, rapid cyclic pressure changes and befouling combustion products. To control some of the effects of the extreme environment and provide more accurate pressure measurements over long-term operation, the following improvements to glow plug integrated pressure sensors have been developed.